Dipper teeth assemblies with means to prevent random reaction points



E 6 LMM H H P April 28, 1970 P DIPPER' TEETH ASSEMBL RANDOM REACTION- Filed June 1 United States Patent 3,508,352 DIPPER TEETH ASSEMBLIES WITH MEANS TO PREVENT RANDOM REACTION POINTS Robert P. Radwill, Oak Lawn, Ill., assignor to Amsted Industries Incorporated, Chicago, Ill., a corporation of New Jersey Filed June 14, 1967, Ser. No. 645,966 Int. Cl. E02f 9/28 US. 'Cl. 37-142 4 Claims ABSTRACT OF THE DISCLOSURE In a dipper tooth assembly having a tooth point capped over a support, predetermined areas of contact between the tooth and the support are provided by means of recesses in selective areas of the tooth point and support that would normally be in contact, thereby preventing random reaction points between the tooth and the support. The recessed areas are so located as to cause stress reduc tion in the corners of the support and near the sides of the tooth.

This invention relates to dipper teeth assemblies for excavating equipment and more particularly to improvements in such assemblies wherein a hollow point is removably capped over a support.

Since excavating teeth assemblies are normally subjected to severe and continual abrasive actions and stresses resulting in relatively short service life, it has become common practice to provide an easily replaceable tooth point on a permanent base that is secured to the excavating equipment. In the use of such two-piece assemblies, the clearances between the support and the tooth point capped thereon have been found to be critical in that failures of such assemblies are often due to undesirable random reaction points between the tooth and the support while under stress. These random reaction points often result in high stress concentrations or create stresses in the relatively weak portions of the tooth assembly, which may cause failure of the tooth.

Accordingly, an object of this invention is the provision of an improved tooth point assembly with superior stress characteristics that does not require extensive modifications of present designs.

Another object is the provision of an improved tooth point and support combination that resolve the reaction points thereon into predetermined areas of the structure, rather than at random locations.

A further object of this invention is the provision of recesses or pads on selective and normally contacting areas of the tooth or support that will tend to distribute external forces to the stronger areas of the structure and prevent high concentration of such stresses, especially in the weaker areas of such structures.

Other objects will become apparent to those skilled in the art from the following description and claims taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a plan view of the improved tooth and support shown in a disassembled relationship;

FIGURE 2 is a view taken substantially along line 22 of FIGURE 1, showing the tooth in cross section and the support in elevation in an assembled relationship;

FIGURE 3 is an end view of the tooth structure, taken substantially along line 3-3 of FIGURE 1; and

FIGURE 4 is a fragmentary end view of a dipper tooth point showing a modification of the present invention.

With reference now more particularly to the drawings, the dipper tooth assembly comprises a support or base 10 and a tooth point 12 adapted for telescopic engagement over the base. Since the base and point are symmetrical about the transverse center plane AA (FIG. 2.) of the base nose, the base 10 and the tooth point 12 are individually reversible.

The base 10 comprises a generally wedge-shaped nose section 14 having upper and lower converging surfaces 16 and 18, respectively, and substantially parallel side surfaces 20, which together with the upper and lower surfaces define a forward edge surface 22. The side surfaces 20 are substantially normal to the transverse center plane A-A of the base. The nose section 14 may also be provided with a shelf 24 insert from the upper and lower converging surfaces 16- and 18 respectively.

The tooth point 12 is also generally wedge shaped and comprises upper and lower external surfaces 26 and 28, respectively, and parallel side external surfaces 30, which merge to form a forward edge 32.

The tooth point 12 has a wedge shaped cavity 34 presenting upper and lower converging surfaces 36 and 38, respectively, and substantially parallel side surfaces 40 merging to form a forward surface 42. The upper and lower converging surfaces 36 and 38, respectively, of the cavity 34 correspond to and mate with respective upper and lower converging surfaces 16 and 18 of the nose section 14. Additionally, the tooth point cavity 34 is provided with upper and lower opposing and spaced ledges 43 on respective upper and lower converging surfaces 36 and 38, which engage corresponding shelves 24 of the nose section 14. Coaligned slots 44 and 46 are provided respectively in the nose section 14 and the tooth point 12 for receiving a retainer pin (not shown).

The present invention represents an improvement over the conventional structure hereinbefore described and comprises one or more recesses in the normally mating or interfitting surfaces of the tooth assembly.

In general, recesses are provided on one or more areas of the interfitting surfaces of the tooth and support such as to expose relatively raised areas for reaction between the tooth and the support and to prevent reaction points at random locations. The relatively raised areas are pref erably located near the sides of the tooth and toward the corners of the support within the tooth cavity.

As shown in FIGURES 13, recesses 48 are provided from the open end of the tooth point 12 inwardly, said recesses being provided on the upper and lower converging surfaces 36 and 38, respectively, spaced from the side surfaces 40 and adjacent to the ledges 42 of the cavity 34. The recesses 48 extend along only a portion of the upper and lower converging surfaces 36 and 38, thereby exposing raised areas 50 along the corners of the tooth cavity 34 to the interfitting nose section 14. The raised areas 50 tend to minimize bending moments on the corners 52 of the tooth point 12, where failures often occur. The recesses 48 are essential only in the lower converging surface 38 if the tooth is non-reversible. However, if the tooth is to be removed and rotated, it has been found expedient to also provide recesses in the upper converging surface 36.

As best shown in FIGURES 1 and 2, recesses 54 may also be provided on the nose section 14 of the base 10, said recesses being located on the upper and lower converging surfaces 16 and 18, respectively, intermediate the extremes of the interfitting portion of the nose section. The recesses 54 on the nose section 14 prevents excessive bending forces thereon by providing positive reaction locations. In addition, recesses 56 may also be provided on the central forward portion of the nose section 14 adjacent the forward edge surface 22 thereof, which tends to equalize any force applied against the nose section between both sides of the nose.

Another modification of the present invention is shown in FIGURE 4. In this instance, the upper and lower converging surfaces 60 and 62, respectively, of the cavity 64 of the tooth 66 are flared'outwardly over the entire area thereof toward the open end of the cavity, as indicated at 67, such that the interfitting support nose (shown in outline at 68) does not contact those tooth cavity surfaces near the open end of the cavity. In this manner, the reaction area between the tooth and the nose is moved forward toward the apex of the tooth, which tends to decrease the bending moment acting near the open end of the tooth.

From the foregoing description, it ma be seen that the present invention has the advantage of greatly increasing the strength of dipper teeth assemblies without materially changing the design of the structure.

It is to be understood that the invention described herein is not limited to the particular tooth and support shown and described herein, but may be applied in any application wherein a tooth is capped over a support, regardless of any particular structure.

Having thus described the invention, what is claimed 1. In a dipper tooth assembly including a support member having a nose and a tooth point having an'open end cavity and capped over said nose in telescoping relal nose, said cavity having a ledge extending centrally along each of said converging surfaces of said cavity from the open end thereof, and a recess in each of the converging surfaces of the nose receiving respective ledges of said cavity, at least one of the converging surfaces of said cavity being recessed from the corresponding converging surface of said nose from the open end of said cavity inwardly in an area adjacent to and on both sides of said ledge, said recesses in said cavity preventing contact between the converging surfaces of the nose and cavity in an area adjacent said ledge and allowing contact between the converging surfaces of said nose and cavity in predetermined areas adjacent to said pairs of side surfaces and the open end of said cavity to thereby prevent random reaction points between said tooth and support.

2. The dipper tooth assembly of claim l wherein said nose is provided with a central recessed area along a portion of both converging surfaces thereof extending from the end surface of said nose, said central recessed areas preventing contact between the converging surfaces of the nose and cavity in an area centrally in said nose adjacent the end thereof and allowing contact between the converging surfaces of said nose and cavity at predetermined areas adjacent to said pairs of side surfaces and end surfaces to thereby prevent random reaction points between said tooth and support. I

3. The dipper tooth assembly of claim 1 wherein recessed areas are provided in both converging surfaces of said nose extending between the central recess therein and both side surfaces thereof, said last-mentioned recessed areas being spaced fro-m the end surface of said nose and from the open end of said cavity when said tooth is mounted on said point and preventing contact between the converging surfaces of said nose and cavity at said recessed areas.

4. A dipper tooth assembly comprising a support member having a nose and a tooth point having an open end cavity and capped over said nose in telescoping relationship, said cavity and said nose having respective pairs of spaced side surfaces and respective pairs of surfaces converging toward respective end surfaces and substantially defining a wedge shape in each of said cavity and said nose, said cavity having a ledge extending centrally along each of the converging surfaces of said cavity from the open end thereof, and a central recess in each of the converging surfaces of the nose receiving respective ledges of said cavity, at least one of the converging surfaces of said nose having a recessed area therein spaced from the corresponding converging surface of said cavity in an area between the central recess in said nose and both side surfaces thereof, said recessed area being located in an area intermediate the end surface of said nose and the open end of said cavity when said tooth point is mounted on said nose, said recess preventing contact between the converging surfaces of said nose and cavity in the area of said recess and allowing contact between the converging sur facesof said nose and cavity adjacent to said recess to thereby prevent random reaction points between said tooth and support.

References Cited UNITED STATES PATENTS EDGAR S. BURR, Primary Examiner 

